Detergent bleach compositions for washing at higher temperatures are well known in the art. As bleaching agent they normally contain a peroxide compound which liberates hydrogen peroxide in aqueous solution, such as the peroxyhydrates, including alkali metal perborates, percarbonates, perphosphates and persilicates, urea peroxide and the like. These bleaching agents are only effective at higher temperatures of the bleaching solution, i.e. from 80.degree. C. up to the boil.
It is known that the bleach activity of peroxide bleach compounds can be improved so as to become effective at lower wash temperatures, e.g. 40.degree.-60.degree. C., by the use of peroxyacid bleach precursors, often also referred to as bleach activators.
Numerous substances have been disclosed in the art as effective bleach activators.
GB Patents 836,988 and 864,798 (UNILEVER) are examples of the earlier patents in the field revealing this technology. They disclose several classes of esters, including the benzoyl ester of sodium phenol sulphonate (SBOBS) and sodium-p-acetoxybenzene sulphonate (SABS).
Another early patent in this field is GB Patent 855,735, which discloses the broad class of "acyl organoamides", to which the currently most widely used N,N,N'N'-tetraacetyl ethylene diamine (TAED) belongs.
A series of articles by Allan H. Gilbert in Detergent Age, June 1967, pages 18-20; July 1967, pages 30-33 and August 1967, pages 26, 27 and 67, disclose a further collection of various bleach activator compounds.
More recent patents disclosing bleach activators are, for example, EP-A-0 120 591; EP-A-0 174 132; EP-A-0 185 522 and U.S. Pat. Nos. 4,412,934; 4,248,928; 4,126,573 and 4,100,095.
Typically, the substances that have been proposed and utilized as bleach activators are organic compounds which react with the perhydroxide anion (OOH.sup.31) of the hydrogen peroxide yielded by the peroxide bleach in the bleaching solution, to form a peroxyacid which is more reactive than the peroxide bleach alone to effect bleaching at bleach solution temperatures of below 60.degree. C. Being a reactive chemistry mechanism, it is easily understood that the effectiveness of bleach activators is determined by factors such as solubility, reactivity, pKa, and type of peroxyacid generated, and that not all bleach activators perform equally well upon each individual stain. For example, a particular type of stain which is effectively removed by one specific peroxyacid precursor-hydrogen peroxide combination, may not be as effectively removable by another peroxyacid precursor/H.sub.2 O.sub.2 system. Since many classes of soiling are encountered in household and industrial practice, there is not one single bleach activator which is effective on all sorts of bleachable soiling and stains. Domestic soils contain hydrophilic and hydrophobic components.
Various attempts have been made to improve the overall bleaching performance on fabrics over a wide range of stains and soilings by bleach system combinations, but such attempts have in general met with only limited success and/or specific drawbacks.
A continuing trend towards even lower wash temperatures has furthermore presented a constant need for peroxide bleaches with real efficacy at temperatures of 40.degree. C. and there below.
EP-A-0 105 690 discloses bleaching compositions consisting of a peroxycarboxylic acid and an aromatic sulphonyl halide bleach activator, which are believed to react and form acyl persulphonates as the bleaching species.
EP-A-0 106 584 (equivalent to U.S. Pat. No. 4,671,891 to HARTMAN) discloses bleaching compositions comprising a mixture of a halogenated peroxybenzoic acid and a carbonyl carbon atom containing bleach activator which together form diacylperoxides, or a mixture of a peroxycarboxylic acid such as diperoxydodecanedioic acid and a long chain acyl-containing bleach activator which together form diacylperoxides.
EP-A-0 257 700 (UNILEVER) discloses the use of a bleach system comprising a percompound and a mixture of TAED and sodium nonanoyloxy benzene sulphonate.
EP-A-0 068 547 (PROCTER & GAMBLE) discloses laundry bleach compositions comprising a mixture of hydrophilic and hydrophobic peroxyacid bleaches, a typical example being a mixture of perlauric acid and diperoxy dodecane dioic acid.
Still, the performances of these prior art systems are far from ideal. Furthermore, diacylperoxides are at least suspicious and sulphonyl halides tend to be relatively unstable.